Inspection of objects, such as but not limited to electrical circuits (wafers, masks, printed circuit boards and the like) can involve mechanically moving an inspection head above the inspected object by a motion system. The motion system can move the inspection head along two or even three axes. An XY motion system can move the inspection head along two axes while a XYZ motion system can move the inspection head along three axes.
The motion system has to be highly accurate and to be characterized by a short damping time. The motion system usually includes rails or other movement control components as well as a moving part (that can include a driving unit or be moved by a driving unit) and optionally auxiliary equipment (such as electrical cards, fiber optic and the like).
FIG. 1 illustrates a part of an exemplary prior art XY motion system 100, in which a pair of parallel horizontal rails 110 are connected to vertical surface 120 (such as a sidewall of rectangular rod, as illustrated in FIG. 1) so that one horizontal rail 110 is positioned exactly above the other horizontal rail 110. The rectangular rod can move along an axis that is perpendicular to the rails, thus providing movement along two axes.
Moving component 130 can move along rails 110 while the center of gravity of a combination of moving component 130 and auxiliary equipment 140 is positioned away from the pair of horizontal rails 110.
FIG. 2 is a side view illustration of the part of the exemplary prior art XY motion system 100. Center of gravity 190 is the center of gravity of moving component 130 and auxiliary equipment 140, and lever distance 192 is the horizontal distance between center of gravity 190 and the pair of parallel horizontal rails 110. The force applied by the mass of moving component 130 and auxiliary equipment 140 over a lever of the length of lever distance 192 can affect the performance of the movement system. This force can deform rails 110. Additionally or alternatively, it can cause moving component 130 to slightly tilt backwards.
There is a need to provide an improved device and method for supporting an optical component of an optical evaluation system.